Automating Manufacturing Systems - Process Control and ...

plc advanced functions - 16.34
3.
I:000/3
assume:
I:000/0 = left orientation
I:000/1 = right orientation
I:000/2 = reject
I:000/3 = part sensor
B3:0/2
B3:1/1
B3:2/0
BSR
File B3:0
Control R6:0
Bit address I:000/0
Length 4
BSR
File B3:1
Control R6:1
Bit address I:000/1
Length 4
BSR
File B3:2
Control R6:2
Bit address I:000/2
Length 4
left
right
reject
4. In MCR blocks the outputs will all be forced off. This is not a problem for outputs such as
retentive timers and latches, but it will force off normal outputs. JMP statements will skip over
logic and not examine it or force it off.
5. Timed interrupts are useful for processes that must happen at regular time intervals. Polled
interrupts are useful to monitor inputs that must be checked more frequently than the ladder
scan time will permit. Fault interrupts are important for processes where the complete failure
of the PLC could be dangerous.
6. These can be used to update inputs and outputs more frequently than the normal scan time permits.
7. The main differences are: Shift registers focus on bits, stacks and sequencers on words Shift
registers and sequencers are fixed length, stacks are variable lengths